NK cell function depends on the balance between inhibitory and activating receptors expressed on the cell surface and how they are organized relative to each other in the NK cell-target cell synapse. For this reason a major goal of the program is to understand the cell biology of human NK cell function. Morphological studies proposed by all four units include localization of NK receptors and ligands in intracellular compartments and examination of their cell surface distribution at the NK cell-target cell synapse. In addition, membrane traffic pathways affecting receptor expression will be defined. All of these cell biological studies involve use of a deconvolution microscope facility to be provided by this Core. To understand the cell biology of individual NK receptors in a controlled context, many of the studies proposed will make use of transfectants produced by introduction of receptors into the NKL cell line or ligands into the 721.221 cell line. In order to produce such transfectants, this Core provides a shared AMAXA Nucleofector instrument. The Core also supports a shared Staff Research Associate (50% effort) who will be supervised by the Director, provide technical assistance for Core utilization and provide training in use of the Core facilities to personnel of the program. The specific aims of this Microscopy and Shared Equipment Core are to 1) support and maintain the deconvolution microscopy facility for the program and 2) purchase, support and maintain an AMAXA Nucleofector.